1. Field of the Invention
This invention relates to compound archery bows. It is particularly directed to an improved rigging system for such bows.
2. State of the Art
Compound archery bows commonly carry assemblies of pulley members (usually called xe2x80x9ceccentricsxe2x80x9d or xe2x80x9ccamsxe2x80x9d) eccentrically mounted on axles in association with respective bow limbs. These limbs extend in opposite directions from a grip (usually comprising a central portion of a handle riser). The rigging for compound bows includes a bow string trained around the pulley members of the system, the string being received by grooves or other features at the perimeters of the pulleys. The eccentric pulley assemblies are conventionally mounted to rotate (pivot) on an axle within a notch at the distal end of the limb, or within a bracket structure carried by the limb tip. The eccentrics include one or more pivot holes substantially offset from center, whereby to provide for a reduction in the holding force felt at the nocking point of the bow string, as the string is moved to its fully drawn condition.
Compound bows and various exemplary pulley assemblies are described by U.S. Pat. Nos. 4,748,962; 4,774,927; and 4,967,721, the disclosures of which are incorporated as a portion of this disclosure.
The rigging for compound bows typically includes cable segments, which may be end stretches extending from an integral bowstring. More often, however, the cable segments are separate elements, each connecting at one end, directly or indirectly, e.g., through structure associated with the pulley assembly, to a terminal end of the bowstring. The remaining (distal) ends of the cable segments are conventionally connected to the opposite bow limb or structure, such as the pivot axle mount of the pulley assembly carried by that limb. In any case, each cable segment includes one or two stretches oriented approximately parallel the bow string. xe2x80x9cApproximately parallel,xe2x80x9d is intentionally fluid in context, merely recognizing that the cable segments and bowstring all extend generally across, but out of contact with, the handle riser portion of the bow between the pulley assemblies, or other structure, carried by the respective bow limbs. All of the cable stretches are thus confined within a space defined by reference planes straddling the handle riser and containing the bow string. The cable stretches are commonly positioned to one side of the bowstring to avoid interference with the nocking point of the bowstring. It is common practice to mount cable guard rods or other structures to the handle riser. These structures are positioned to physically hold the cables away from the plane of travel of the bowstring.
With a compound bow oriented in its normal position of use, it is conventional to consider the bow as being oriented vertically. Unless otherwise stated, the bows referred to in this disclosure are assumed to be in this xe2x80x9cverticalxe2x80x9d orientation. The handle riser is thus considered to have an xe2x80x9cupper endxe2x80x9d and a xe2x80x9clower end.xe2x80x9d The limb extending from the upper end of the handle riser may be referred to as xe2x80x9ca first limbxe2x80x9d or the xe2x80x9cupper limb,xe2x80x9d in either case terminating in an xe2x80x9cupper limb tip.xe2x80x9d Corresponding terminology is applied to the xe2x80x9csecond limb,xe2x80x9d which extends from the lower end of the handle riser. The bow string is assumed to travel in a plane of travel between a fully drawn condition and braced or at rest condition. Cable stretches may be viewed as being positioned to the left or right of the plane of travel of the bowstring, recognizing that in some rigging systems, a cable stretch may be to one side of that plane of travel along the first limb and to the opposite side of that plane of travel as the stretch proceeds to its point of attachment at the second limb. The variety of rigging configurations present in the field is explained in part by different approaches taken by bow designers with respect to the balancing of forces applied to limb tips, axles, limb mountings and other bow components by the cable stretches under actual use conditions. Some compound bows have required the use of multiple cable guards to assure sufficient arrow clearance, because of the close proximity of the cable stretches to the travel plane of the bowstring. upper and lower cable guards have been used, for example, in bow constructions in which cable stretches are positioned both to the left and to the right of the bowstring.
This invention provides a rigging system comprising first and second pulley assemblies, mounted to pivot on axles mounted at tips of corresponding first and second limbs of a compound bow constructed in generally conventional fashion. Each assembly includes a central string pulley component with a peripheral string groove. The string pulley components are either identical or mirror images of each other in configuration. They may be of various cross sectional configuration, but are most conveniently circular. They may be mounted concentrically; that is, to pivot around their geometric centers, but are preferably mounted eccentrically; that is, to pivot around respective axes displaced from their geometric centers. Opposite ends of a bowstring are connected directly to the respective pulley assemblies such that, at rest condition of the bow, the peripheral string grooves are substantially occupied by wrapped bowstring.
Straddling the string pulley component of each assembly are first and second cable pulley components, each having peripheral cable groves. These components are congruent with respect to each other, and may also be of various cross sectional shape, including circular, but they are usually non-circular. A first cable segment is carried by the first pulley assembly, such that opposite end portions (cable end stretches) of that cable segment extend from the respective cable grooves of the assembly, across the grip portion of the bow, to anchor to the second limb, preferably with respective terminations fastened to opposite sides of the axle mounting the second pulley assembly. A second cable segment is carried in identical fashion by the second pulley assembly, with its terminations anchored to the first limb.
In most instances, the midpoints of the cable segments will be located internal the pulley assembly proximate the transverse center of the string pulley. The cable segments may be xe2x80x9cfloatingxe2x80x9d with respect to the pulley assemblies; that is, the midpoints of the respective cable segments may be free to shift slightly in position in response to unequal forces seen by the respective end stretches of a cable segment. Alternatively, the first and second cable segments may be physically anchored to the respective first and second pulley assemblies to hold the cable midpoints in substantially fixed lateral position with respect to the axles associated with the respective pulley assemblies.
The pulley assemblies may be structured with sufficient width to permit passage of a launched arrow between the cables, without the use of a cable guard. In certain embodiments, however, cable spreading structure is positioned between the cable segments located on opposite sides of the bow string. Such cable spreading structure may be mounted to extend from the handle riser to between cable stretches located to the right and left of the bowstring. The cable spreading structure is structured and arranged to hold those left and right cable stretches away from the vicinity of the bow string while permitting free travel of the nocking point of the bowstring from fully drawn to braced position. In a currently preferred arrangement, a plate is mounted to extend in cantilever fashion from the handle riser between the left and right cable stretches. An open slot or channel in the plate accommodates movement of the bowstring, while the edges of the plate maintain adequate spacing of the cable stretches as the bowstring is drawn or released. Interface fixtures may be positioned between the plate edges and the cable stretches to reduce friction and wear on the cable. The interface fixtures may be configured in a variety of specific forms, provided they are constructed and arranged to travel along the edges of the plate while providing a mobile anchorage for the cable segments. Alternative arrangements substitute approximately parallel rods extending, preferably from a mounting fixture, from the handle riser.
A compound archery bow construction which benefits from the cable spreading structure of this invention typically comprises a handle riser, with upper and lower respective ends; a first bow limb, extending from the upper end of the handle riser to terminate in a distal upper limb tip; a second bow limb, extending from the lower end of the handle riser to terminate in a distal lower limb tip; rigging such as that previously described, or at least comprising first and second pulley assemblies mounted to pivot on axles carried by the upper and lower limb tips, respectively, the rigging including a central bow string and a plurality of cable stretches extending approximately parallel the bow string between the upper and lower limb tips such that the bow string is located between left and right cable stretches. That is, one cable stretch extending from each pulley assembly is located to the right of the bowstring, and one other cable stretch extending from each pulley assembly is located to the left of the bowstring (more precisely, the reference plane intersecting the bowstring axes during all positions of its normal travel).
The cable spreading structure typically extends from the handle to between the left and the right cable stretches; it is generally structured and arranged to hold the left and right cable stretches away from the vicinity of the bow string, while permitting free travel of a nocking point of the bowstring from fully drawn to braced position. The cable spreading structure may take a variety of specific forms, but one particularly effective version includes a plate element with a distal slot configured to accommodate movement of the bowstring. The plate is a component of an assembly which includes a traveling fixture with a first element constructed and arranged to retain an adjacent cable stretch, and a second element constructed and arranged to couple in sliding engagement with an edge of the plate. As applied to a compound archery bow with rigging structured and arranged as illustrated by the accompanying drawings, with an end stretch of each of the cable segments positioned to the right of the bowstring and an end stretch of each the cable segments positioned to the left of the bowstring, the plate may be relatively thin to present approximately parallel right and left edges. The assembly may then include a first traveling fixture with a first element constructed and arranged to retain those of the cable end stretches located to the right of the bowstring and a second element constructed and arranged to couple in sliding engagement with the right edge of the plate. Such an assembly may further include a second traveling fixture with a first element constructed and arranged to retain those of the cable end stretches located to the left of the bowstring and a second element constructed and arranged to couple in sliding engagement with the left edge of the plate.